Microsoft and Open Source: An unofficial timeline

The profound cultural transformation towards open source did not happen overnight at Microsoft. This is an unofficial timeline of Microsoft's embrace of open source.

Microsoft and Open Source: An unofficial timeline

The profound cultural shift towards open source did at Microsoft was the result of sustained efforts within the company by open source advocates. Microsoft's shift is a model for positively transforming organizations. It is also a testament to the power of collaboration in technology. After Build 2020 it is now clear Microsoft is a Linux and open source company.

This is a very brief timeline of Microsoft's evolution into an open source leader. It is an attempt to provide historical context of a two-decades-long process. An open source version of this post is maintained on GitHub.

This is not endorsed by Microsoft, Canonical, or any person, company, or project mentioned here.



  • Microsoft begins experimenting with 'shared source', including SSCLI, the core of .NET


  • WiX, the first project from Microsoft under an OSS approved license, is released
  • Begins cross-licensing software patents with Linux vendors


  • F# released under the Apache 2.0 license


  • CodePlex announced
  • Ports PHP to Windows, upstreams code under PHP license
  • Partners with Novell to improve open source interoperability


  • Open Source Initiative approves the Microsoft Public License (MS-PL) and Microsoft Reciprocal License (MS-RL)
  • Provides access to Windows NT kernel source for research to universities
  • Open sources IronRuby and IronPython under Microsoft Public License
  • Open sources xunit under Microsoft Public License
  • Reaches agreement with EU to reduce costs of licensing patents and specifications
  • Scheduled to exit US DOJ antitrust oversight, voluntarily agrees to extended oversight


  • Forms Open Web Foundation with Google, Facebook, Sun, IBM, Apache, and others
  • Joins Apache Software Foundation
  • Releases source for Singularity, an experimental OS to CodePlex
  • Begins distributing the open source jQuery JavaScript library with Visual Studio
  • Acquires Powerset, it's first open source acquisition, upstreams code from HBase to Apache Hadoop


  • Begins contributing to Linux kernel
  • Forms independent CodePlex Foundation, later known as Outercurve Foundation to promote open source
  • Open sources ASP.NET MVC under the Microsoft Public License
  • Apologizes after download on website is found to have GPL code, properly open sources download
  • Promises not to enforce patents against open source implementations of C#, e.g. Mono
  • Settles a dispute with TomTom over FAT32 software patents, avoiding further conflict with open source
  • Reaches settlement with EU to provide users a choice of web browsers on Windows installation
  • Platform Strategy Group begins an internal push for embracing open source
  • "Burning the Ships: Transforming Your Company's Culture Through Intellectual Property Strategy" is published on Microsoft's embrace of open collaboration
  • "Has Microsoft lost its war on open source?" InfoWorld


  • Signs Joomla! Contributor Agreement and upstreams improvements
  • Relicenses IronRuby and IronPython under Apache License 2.0
  • "Microsoft: 'We love open source'" Network World


  • Acquires Skype, maintains Linux client
  • Begins contributing code to Samba
  • Exits antitrust oversight by US DOJ
  • Ports Node.js to Windows, upstreams code under Apache 2.0
  • ­čô░ "Microsoft Embraces Elephant of Open Source" Wired


  • Azure begins hosting Linux virtual machines
  • Codeplex supports git
  • Begins contributing to git and collaborates with GitHub on LibGit2
  • Ports Apache Hadoop to Windows, upstreams code under MIT
  • Open sources ASP.NET, MCV, Razor, and Web API under Apache 2.0
  • Open sources React Extensions and IL2JS under Apache 2.0
  • Forms Microsoft Open Technologies, Inc.
  • Releases TypeScript under Apache 2.0, first Microsoft project on GitHub
  • Canonical closes Ubuntu bug #1
  • ­čô░ "Microsoft opens up" O'Rielly


  • Steve Ballmer resigns
  • VM Depot announced, community-driven repository of Linux and BSD virtual machines for Azure
  • Microsoft challenges broad US warrant for overseas e-mails and helps create a new law improving e-mail privacy
  • xunit transferred to Outercurve Foundation, relicensed under Apache 2.0
  • ­čô░ "Microsoft's Open Source Company Is a Year Old. But What Is It?" Wired


  • Satya Nadella appointed CEO
  • The full .NET stack, Microsoft's flagship development toolkit, is open sourced and contributed to .NET Foundation
  • Implements AllJoyn support in Windows, contributes code upstream
  • Creates official GitHub presence
  • Releases Wireless Display Adapter, first hardware device to use embedded Linux
  • Contributes to OpenJDK
  • "Microsoft loves Linux." - Satya Nadella
  • ­čô░ "More open-source at Microsoft? You'd better believe it" VentureBeat


  • Visual Studio Code released, releases Linux build
  • Co-founds Node.js Foundation
  • Joins R Foundation
  • Forms Open Source Programs Office, tasked with enabling and normalizing open source across the company
  • Open sources Matter Center, Microsoft's legal practice management software
  • Open sources Chakra, legacy Microsoft EdgeÔÇÖs JavaScript engine
  • ­čô░ "How Open Source Is Shaping Microsoft's Future" RedmondMag


  • Windows Subsystem for Linux announced in partnership with Canonical
  • Joins Linux Foundation
  • Open sources PowerShell, releases Linux build
  • Begins porting Sysinternals to Linux
  • Acquires Xamarin, relicenses Mono under MIT license
  • Acquires LinkedIn, maintains Apache Kafka as open source
  • SQL Server released for Linux
  • Begins hosting Linux Foundation courses on edX
  • SONiC released, based on Debian GNU/Linux
  • Begins opening Reactors worldwide for use by entrepreneurs and open source communities
  • "The company has become an enthusiastic supporter of Linux and of open source and a very active member of many important projects." - Jim Zemlin, Executive Director of The Linux Foundation
  • ­čô░ "Why Microsoft is turning into an open-source company" ZDNet


  • Satya Nadella releases "Hit Refresh: The Quest to Rediscover Microsoft's Soul and Imagine a Better Future for Everyone" describing his vision for an open and collaborative Microsoft
  • Forms Open Source Programs
  • Joins Open Source Initiative
  • Joins Cloud Native Computing Foundation
  • Joins MariaDB Foundation
  • Acquires Deis
  • Open sources Git Virtual File System (GVFS), the work done moving Windows to git
  • Opens Microsoft Store to open source applications
  • Better privacy controls, privacy dashboard, and diagnostic data transparency introduced in Windows
  • Announces Linux development with C++ in Visual Studio
  • Gives keynote at Open Source Summit North America
  • Moves Windows development to git
  • ­čô║ Microsoft Loves Open Source: Becoming the Largest Contributor - GitHub Universe 2017
  • ­čô░ "How Microsoft Is Shifting Focus to Open Source" The New Stack
Satya Nadella gives background on Microsoft transformation


  • Joins Open Innovation Network, cross-licenses 60,000 patents with open source community
  • Acquires GitHub
  • "We are all in on open source." - Satya Nadella
  • GitHub Actions is released, providing free CI/CD for open source projects
  • Windows Subsystem for Linux 2 announced powered by Linux kernel
  • Begins using Citus and PostgreSQL on Ubuntu to analyze telemetry from Windows test builds on employee devices
  • PowerShell released as a snap
  • OpenSSH included in Windows
  • Shifts their mobile application strategy to Android, begins contributing to Android developer ecosystem
  • Windows Calculator released as open source
  • ­čô░ "Microsoft may be the world's largest open source contributor" TechRepublic


  • Visual Studio Code released as a snap
  • GitHub announces GitHub Sponsors, lowers prices
  • Edge browser released based on open source Chromium
  • Linux surpasses Windows usage on Azure
  • Begins adopting open source-style collaboration internally
  • Teams released for Linux
  • Acquires Citus Data, maintains open source project
  • Joins OpenChain
  • Admitted to Linux-distros security mailing list
  • Files amicus brief at the US Supreme Court in support of open source and Linux
  • Creates Open Application Model with Alibaba Cloud as a Open Web Foundation project
  • Releases new Windows Terminal and PowerToys as open source
  • Published exFAT as open specification, contributes patents to OIN, and upstreams driver to Linux kernel
  • Stores all public GitHub repos for 1,000 years in Svalbard, Norway
  • Joins Unified Patents Open Source Zone to defend open source from patent trolls
  • Announces Android-based smartphone, Surface Duo, with a Linux kernel
  • Announces Microsoft Defender for Linux
  • Open sources SPTAG, a crucial search algorithm used by Microsoft
  • Open sources SandDance, a data visualization tool
  • Open sources the Microsoft C++ Standard Library
  • Open sources Interpret ML
  • Open sources Quantum Development Kit, a quantum computing SDK
  • Satya Nadella speaks at Red Hat Summit
  • Richard Stallman speaks at Microsoft, states "we should not maintain a burning grudge over actions that ended years ago"
  • Linux Torvalds quoted at Linux Plumbers Conference as saying Microsoft "have changed"
  • JS Foundation and Node.js Foundation merge to form OpenJS Foundation, Microsoft contributes Electron to OpenJS Foundation
  • Scott Hanselman gives keynote at NDC London laying out Microsoft's open source vision
  • ­čô░ "Microsoft: The open source company" Ars Technica


  • Acquires npm, the Node package manager
  • Hosts WSLConf, the first conferenced dedicated to WSL
  • Microsoft president Brad Smith admits being wrong about open source
  • Edge browser port to Linux seen at Build
  • Pushes improvements to Chromium upstream
  • Releases open source Windows Package Manager
  • Open sources dataset to help fight COVID-19-related cybersecurity threats
  • Open sources Java extension for SQL Server
  • Open sources MSQuic, a Windows NT kernel library for QUIC
  • Open sources Petridish, a neural architecture search algorithm for deep learning
  • Open sources Project Rocket, a software stack to perform live video analysis by AI/ML
  • Open sources Project Bonsai, a machine teaching service
  • Open sources Application Inspector, cross-platform source code security analyzer
  • Open sources TensorWatch, a debugging tool for AI and deep learning
  • Open sources Project Verona, a memory-safe research language
  • Upstreams open source improvements to QNNX natural language model
  • Linux-based Azure Sphere OS released
  • Announces plans to open source Fluid Framework
  • Announces Python for Excel
  • Ad features Ubuntu on Surface Book 3
  • ­čô░ "MicrosoftÔÇÖs romance with open source software is on display at Build 2020" Ars Technica

Known Open Source Collaborations

  • Canonical
  • Red Hat
  • SuSE
  • Debian
  • IBM
  • Oracle
  • Google
  • Chef
  • Puppet
  • Redis Labs
  • Elastic
  • Samsung
  • Cloudera
  • Docker
  • Nokia
  • HashiCorp
  • PostgreSQL
  • Kali Linux
  • Whitewater Foundry
  • Allianz
  • React
  • Flutter
  • HashiCorp
  • Nvidia
  • BMW
  • Apache Cassandra
  • Apache Kafka
  • Apache Hadoop
  • Apache Spark
  • Linux Foundation
  • Cloud Native Computing Foundation
  • Eclipse Foundation
  • OpenDaylight
  • Open Container Initiative
  • R Consortium
  • F# Foundatoin
  • .NET Foundation
  • Open API Initiative
  • Confidential Computing Consortium
  • OpenChain
  • TODO Group
  • Open Source Initiative
  • Apache Software Foundation
  • iZootoo
  • Linux Containers on Windows
  • Azure Arc
  • Azure Databricks
  • Azure Linux virtual machines
  • Azure Linux containers
  • Azure-tuned Linux kernel
  • Azure Spring Cloud
  • Azure DevOps
  • Azure HDinsight
  • GitHub Actions
  • Microsoft Defender for Linux
  • StorSimple

Select Open Source Projects

The list below is incomplete. current lists 1,155 open source projects at Microsoft and it would not be possible to curate them all here.

Here is a list of selected projects:

Dev Tools


Web Dev Tools

  • Edge dev tools
  • Playwright - Node library to automate Chromium, Firefox and WebKit with a single API
  • Blazor




  • Azure CLI
  • Open Enclave SDK - A hardware-agnostic open source library for developing applications that utilize hardware enclaves.




  • WorldWide Telescope - A visualization environment that brings together imagery from the world's best ground- and space-based telescopes
  • Project Mu - The UEFI core used in Microsoft Surface and Hyper-V

Programming Languages

  • TypeScript - Programming language similar to JavaScript, among the most popular on GitHub
  • Bosque - An experiment in regularized design for a machine assisted rapid and reliable software development lifecycle
  • Verona - Research programming language for concurrent ownership
  • SPTAG - A library for fast approximate nearest neighbor search
  • P - A language for asynchronous event-driven programming

More Open Source at Microsoft

Historic Open Source Contributions

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